, and people have said it's very helpful. >> reporter: steve horwitz sells a broad variety of medical marijuana products in his south denver store, ganja gourmet. >> there are all kinds of chocolates and cookies and brownies. >> reporter: his is just one of 500 such dispensaries which have opened over the last four years, ever since colorado started allowing stores to sell the drug for medical uses. since then, a large market has flourished, and more than 100,000 residents now carry physician-recommended cards allowing them to buy the drug. but passage of a ballot initiative known as "amendment 64" will likely take retail marijuana to a whole new level, since presumably anyone who can now buy alcohol will be allowed to buy the drug. horwitz said almost as soon as the votes were counted last week, he began to hear from potential customers. >> and then all day long, the phone was ringing off the hook. they're pot tourists. they want to come to colorado and they want to do like they do in amsterdam. >> reporter: but those would-be high fliers probably shouldn't start booking plane tickets yet. hor